1. Field of the Invention
This invention relates to NBC barrier adhesive tape structures useful for the repairing, sealing and reinforcement of NBC (nuclear, biological and chemical) protective materials that are for use in garments for personnel, shelters, tents, covers for equipment and supplies and the like. The NBC barrier adhesive tape structure may be a laminated barrier structure composed of multilayer plastic films and, in particular, to a composite, laminated plastic material which includes a layer of fabric substrate, and a layer of pressure sensitive adhesive covered by a layer of release liner and, alternatively, self wound without a release liner.
2. Description of Prior Art
Plastic barrier materials are involved in an almost unlimited range of products and applications. Containers, wrappers, pouches and bottles of varying degrees of flexibility for foods, pharmaceuticals, chemicals, and other products are commonplace. In addition to containing and protecting products, barrier materials are used to protect equipment and even personnel from a wide range of environmental hazards. One application of such barriers having particularly stringent demands is that of protecting military personnel, equipment, and supplies against (NBC) Nuclear, Biological and Chemical warfare agents. NBC barrier materials are used for protection of personnel, shelters, tents, equipment and supplies. The NBC fabrics are fabricated into protective shelters, tents, tarpaulins and covers for equipment and supplies and even protective clothing for personnel.
In addition to needing NBC barrier fabrics, there is also a need for an additional material that may be used in the repair, sealing, and reinforcement of these NBC barrier materials. The qualities of NBC barrier adhesive tape with sealing, repair and reinforcement qualities has many uses in the initial manufacturing, deployment and in field set up for sealing, maintenance and repair of the many NBC protective materials and end items. Such NBC barrier adhesive tape can extend the useful life of flexible and rigid NBC materials used in shelters (flexible and rigid), tarps, protective covers, collective protection tents, mobile equipment (aircraft, motorized vehicles, marine vessels) and personnel protective clothing by sealing, patching, and reinforcement of holes, cuts, tears or punctures in most any NBC material. Another important use is the taping over seams of previously unsealed and overlapping NBC materials or to reseal previously fastened but poorly sealed seams, or to tape over unsealed sewed or stapled seams or for the reinforcement of a variety of sealed seams that are subject to separating under normal use, fatigue, stress or wear.
Another important use of the NBC barrier adhesive tape structure is in the sealing and reinforcement of multi track extruded plastic zipper fastener systems, such as ITW's, Somerset, N.J. maxigrip extrusion profile plastic zippers which may be used in modular collective protection shelters, tents, tarpaulins, covers, protective clothing and the like.
Whether in the initial manufacturing, deployment, or field use of the above-mentioned items, there is a need for NBC adhesive barrier tapes. The NBC barrier materials may be repaired, sealed and reinforced so that they may continue to protect against a wide range of chemical and biological agents if they are damaged, worn, modified, etc. The pressure adhesive tape should also provide a barrier and resist penetration of NBC agents in various forms, solids, liquids, gases, and dust, including radioactive dust.
In addition to containing and protecting products, barrier materials are used to protect equipment and even personnel from a wide variety of environmental hazards. Here, in addition to being a barrier fabric, there is a need for a pressure sensitive adhesive tape material for use in the repair, sealing, and reinforcement of these materials so that they may continue to protect against a wide range of chemical and biological agents. The pressure sensitive tape should also provide a barrier and resist penetration of chemical and biological agents in various forms, solids, liquids, gases, dust, including radioactive dust. It should be easily made resistant to deterioration from ultraviolet light when used in long term outdoor applications and be readily disposable by military and industry standards. Of course, the adhesive tape should also be durable, lightweight, and very flexible so it can easily conform to the shape of the surface of the material to which it is being applied and be easily fabricated into various shapes, such as rolls of tape, patches disks and the like. In some instances where the barrier adhesive tape structure is to be used by the military in protective garments, covers, shelters and equipment enclosures of various colors, it should be made in a natural, clear color so it will appear to take on the color of the material it is applied to and make detection from the air or ground more difficult. It may also be made with an outer surface in a mat finish and dull color to escape detection from the air when applied to materials having a need for additional concealment. Yet again, in some instances where fire retardant barrier materials are being used in protecting military personnel, equipment and supplies, the barrier adhesive tape materials should be made fire-retardant. The outer surface should also be “printable” in that it should easily accept printed patterns such as those needed for camouflage or identification.
Because the attainment of some of these qualities often results in the sacrifice of others, e.g. the addition of the NBC barrier film to a pressure sensitive tape material may affect its flexibility, there is not presently available a material which satisfies the needs of the military or the commercial, industrial markets.
One of the better-known commercial films sometimes used as a barrier is the copolymer of vinylidene chloride and vinyl chloride, such as Saran® films, available from Dow Chemical Company, Midland, Mich. This material has a high resistance to attack by a wide range of chemicals, it has low permeability to gases and vapors, and it has high transparency. Moreover, it can be bonded or sealed to itself and to many other materials and substrates for special applications. The Dow Chemical Company has made and sold widely, combinations of SARAN® films and outer layers of polyolefin resins including low-density polyethylene (LDPE) and ethylene vinyl acetate (EVA), such as SARANEX® films. The SARANEX® films in turn have been further laminated or bonded to other materials. These films are, and have been, limited to four and five layer constructions and range in the 1.5 mil to 5 mil thicknesses.
Other multilayer films for protection use have been disclosed. For example, Henriksen describes a 3 layer barrier film (PE/*PVAE-1/PE) [PVAE is the symbol used to designate Vinyl Alcohol-ethylene copolymer] for protecting skin against hazardous chemicals in gloves, boots, hoods and coverall suits by positioning a protective garment adjacent to the skin and said protective garment comprising substantially water insoluble polymer material, as described in U.S. Pat. No. 4,902,558 and U.S. Pat. No. 5,059,477—an improvement designed to protect against epoxides and other hazardous chemicals. Such comprises a water insoluble polymer membrane shaped by extrusion or casting and or seamed by heat sealing or sewing into a glove, coverall suit, hood or boot. Also understood is a composite 5 layer composite chemical barrier film (Polyethylene/Adhesive/EVOH*/Adhesive/Polyethylene) [*EVOH is the ISO standard symbol for Ethylene Vinyl Alcohol], used in protective gloves which provides permeation protection of up to 24 hours against over 250 chemicals and chemical mixtures per ASTM F739, “Standard Test Method for Resistance of Protective Clothing to Permeation by Liquids and Gases” is further described in literature published (Form# 4H-PP-392) © 1992 by Ansell Industries Inc, Coshocton, Ohio and further described in the Ansell Protective Products publication, 6th Edition Form No. CRG-GC-Rev. 9-98, © 1998.
Tung in U.S. Pat. No. 5,250,350 discloses a modified burn characteristic SARANEX® film in the form of a four or five layer film product. Additionally, Boye et al., describes in U.S. Pat. No. 5,162,148 a laminated material comprising a polyolefin nonwoven substrate and a 5 layer co extruded film with a polyolefin outer layer and an intermediate layer selected from a group comprising ethylene-hydrolyzed vinyl acetate copolymer and polyethylene terephtalate coated with polyvinylidene chloride for manufacturing protective equipment against NBC attacks. Similarly, Smith, Jr., in U.S. Pat. Nos. 4,970,105 and 5,082,721 describes a fabric used in the manufacture of protective garments, containers and covers comprising an inner layer of a tear resistant, high tensile strength substrate and a film layer comprised of a fusible, meltable, polyhalogenated ethylene resin group bonded on at least one surface of said high modules fabric substrate. Bartacis discloses a multilayer structure in U.S. Pat. No. 4,924,525. This reference describes a multilayer film structure having an inner layer of substantially isotactic oriented polypropylene homopolymer sandwiched between a layer of ethylene-propylene random copolymer and a layer of ethylene-vinyl-acetate. The multilayer film structure is then bonded to a two layer polyester substrate using an elastomeric adhesive. In a preferred embodiment, a barrier material having a layer of ethylene-vinyl alcohol is combined with the multilayer film structure to form a composite, which is then combined with the substrate. Additionally, Adiletta, in U.S. Pat. No. 4,865,903, describes a flexible, impermeable, universally chemically resistant composite structure which may be fabricated into protective clothing. The composite structure comprises a fabric substrate and thermally-melt-bonded on both sides thereof, a coated film, which film comprises a PTFE film having a thermoplastic flouropolymer coating on both sides thereof. Reference is made to US Army Drawing 5-19-13821, “Roll, Repair Tape”. The drawing is notated that the drawing's technical data is “Export Restricted” by the Arms Control Act (title 22, U.S.C. Sec 2751 of the Export Administration Act of 1979, as amended. The technical information disclosed in the drawing is also governed by the International Traffic in Arms regulations. Additional references for adhesive tapes are cited in the following U.S. patent documents.
3,394,799July, 1968Ritson428/3543,716,437February, 1973Newman428/3544,303,724December 1981Sergent428/3544,705,715November, 1987Decoste428/3544,740,416April, 1988Decoste428/3544,992,331February 1991Decoate428/3545,108,815April 1992Adams428/3546,183,861February 2001Carroll428/354
Despite the foregoing disclosures, there is still a need for an adhesive tape material that also serves as a NBC barrier adhesive tape structure that will protect against nuclear, biological and chemical agents that is very flexible, thin gauge, light weight, durable, with excellent adhesion properties to a variety of NBC materials and coatings that can be used specifically in the repairing, sealing and reinforcement of nuclear, biological and chemical (NBC) protective materials (rigid and flexible) used for protective garments, covers, tents and shelters for personnel, equipment and supplies. Currently, repair, sealing, reinforcement of NBC fabrics requires heat sealing or sewing and specialized tools and skills which are not readily available for in field repair. Additionally, rigid NBC materials require special type gasketing materials and sealants at seams, doors and covered openings. There is not currently a NBC barrier adhesive tape material which satisfies the NBC barrier, adhesion, flexibility needs required by the military and industry. Thus, an NBC barrier adhesive tape structure is a quick, easy, inexpensive, practical alternative that allows the NBC material to be placed back in service after the needed service (repair, seal or reinforcement) is completed. NBC protection materials which have been damaged by holes, tears, seam separations, punctures and the like including stress point reinforcements can be performed in the field, quickly and inexpensively.
There is a need for such a barrier structure also having antistatic properties. There is also a need for such a barrier structure also having fire-retardant properties. Reference is made in this connection to my prior U.S. Pat. No. 5,344,697 granted Sep. 6, 1994, U.S. Pat. No. 4,975,316, and U.S. Pat. No. 5,811,359, the contents of which are hereby expressly incorporated herein by reference.
The reinforcing fabric substrate will impart the necessary strength to the multilayer barrier film and the resulting laminated composite structure is resistant to NBC agents and is coated on one side with a pressure sensitive adhesive and covered with a protective release liner material. The composite NBC barrier adhesive tape structure may also be resistant to burning, or be self extinguishing, and may also be antistatic. The NBC adhesive barrier material may use a silicone coated or similar releasing coating on the release liner that is placed over the pressure sensitive adhesive to prevent the material from sticking to itself and to protect the adhesive when wound in roll form. Alternatively, when desired, the NBC adhesive structure may also be made without the release liner by having the side opposite the adhesive surface treated with one of the commonly used methods of release coating to prevent the permanent sticking or blocking of the adhesive to the opposite side of the barrier structure. Such NBC barrier adhesive tape structures made in accordance with the invention, offer “hold out” and resistance to the permeation of a variety of chemical warfare agents, for example, Mustard and Thickened GD in addition to also holding out against toxic biological and nuclear agents. As may be determined from the foregoing composite adhesive tape materials, however, none provides such a combination of unique properties or protection from these NBC agents.